The company is no longer accepting new Backpack customers, though existing users can still log in and continue to be supported.

The reason for phasing out Backpack is fairly straightforward. As 37signals itself notes on Twitter, the most recent version of its Basecamp project management solution was completely rebuilt from the ground up and includes most of the features Backpack users are familiar with, and of course much more.

37signals initially launched Backpack in 2005. Judging by Twitter chatter, it seems like they quietly removed it from their homepage earlier this month, and redirected the Backpackit.com without making any formal noise about its decision.